The effects of declines in nutrient concentrations had been intensively studied in freshwater lakes (e.g. Jeppesen et al., 2002, Jeppesen et al., 2005 and Søndergaard et al., 2002), and most have reported improvements in water quality. Water quality improvement is mainly achieved through the decrease in
tsa trichostatin biomass. This decrease can occur as a direct response to declines in nutrient concentrations, but it can be further facilitated through increased grazing pressure from zooplankton grazers (Edmondson, 1994) and the recolonization of submerged macrophytes, which has been shown to substantially affect the success rates of water quality improvement in lakes (Mehner et al., 2002). While there may be differences between freshwater and marine systems in their responses to declines in nutrient concentrations (Cloern, 2001 and Smith et al., 1999), examples of dramatic improvements in once eutrophicated marine ecosystems such as Hillsborough Bay, Florida (Johansson and Lewis, 1992) and the coastal waters of Denmark (Rask et al., 1999) had both involved the recolonization of macrophytes such as seagrasses (Hillsborough Bay) and eelgrass (Denmark). However, an early study in Tolo Harbour has shown
species richness most of the harbour was covered by extremely fine sediments that support little plant life (Trott, 1972). Therefore, even with the decline of nutrient concentrations and increase in water transparency, the spread of macrophytes in Tolo Harbour is unlikely.
